Black liquor is a fluid that is the by product of the pulping process. This fluid contains both organic and inorganic material resulting from the pulping of wood. Black Liquor is burnt in a special boiler where the heat from the organic matter is used to generate steam and the inorganic matter is reduced to extract the pulping chemicals which are then returned to the pulping process. In order to ensure the proper combustion and chemical recovery the liquor has to be atomized to an optimum size. This depends on the boiler geometry as well as operating parameters such combustion air flow, liquor flow rate, injection pressure and temperature.
In accordance with the prior art, black liquor is sprayed into the boiler through dedicated nozzles. FIG. 1 is a schematic of the most widely used nozzle, the splash plate 10. Other nozzles types that have been used are used the V-jet 20 shown in FIG. 2 and more recently the beer can 30 shown in FIG. 3. The latter has come about as a result of new developments in boiler combustion.
In the case of the splash plate nozzle the black liquor is delivered through the pipe 14 which is mounted to the inlet orifice 11 on the nozzle body 13. The fluid leaves the nozzle through the discharge orifice 12. Both the inlet and discharge orifices 11 and 12 are an integral part of the nozzle body 13. The fluid upon leaving the orifice impacts on the splash plate 15 where it spreads out to form a sheet that eventually breaks up into droplets that burn.
For the V-jet nozzle 20 the fluid is delivered through pipe 24 which is mounted to the inlet orifice 21 found on the nozzle body 23. The fluid leaves the nozzle through the discharge orifice 22. Both the inlet and discharge orifices 21 and 22 are an integral part of the nozzle body 23. Fluid traveling through the discharge orifice contracts and spreads out like a fan forming a thin sheet that eventually breaks up into droplets that burn.
For the beer can nozzle 30 the fluid is delivered through pipe 34 which is mounted to the inlet orifice 31 found on the nozzle body 33. The fluid leaves the nozzle through the discharge orifice 32. Both the inlet and discharge orifices 31 and 32 are an integral part of the nozzle body 33. Fluid traveling through the inlet orifice 31 travels down a small transition channel 35 and enters the inner cavity 36 of the nozzle body 33 at a point tangential to the cavity wall. The fluid swirls around the cavity and eventually leaves the nozzle body 33 through the discharge orifice 32 found at the bottom of the nozzle body. The fluid leaving the discharge orifice spreads like a cone which eventually breaks up into droplets that burn.